Looking directly at the sun is unsafe during the solar eclipse, and the only safe way to look directly at the un-eclipsed or partially eclipsed sun (before/after the full eclipse has taken place) is through special “eclipse glasses” with solar filters, warns NASA, which offers these tips:
- Homemade filters or sunglasses are not safe for looking at the sun. Five manufacturers have certified that their eclipse glasses and handheld solar views meet international standards, and they are Rainbow Symphony, American Paper Optics, Thousand Oaks Optical, TSE 17 and Baader Planetarium.
- Always inspect your solar filter before use; if scratched or damaged, discard it. Read and follow any instructions printed on or packaged with the filter. Always supervise children using solar filters.
- Stand still and cover your eyes with your eclipse glasses or solar viewer before looking up at the bright sun. After glancing at the sun, turn away and remove your filter — do not remove it while looking at the sun.
- Do not look at the un-eclipsed or partially eclipsed sun through an unfiltered camera, telescope, binoculars or other optical device. Similarly, do not look at the sun through a camera, a telescope, binoculars or any other optical device while using your eclipse glasses or hand-held solar viewer — the concentrated solar rays will damage the filter and enter your eye(s), causing serious injury. Seek expert advice from an astronomer before using a solar filter with a camera, a telescope, binoculars or any other optical device.
- If you are within the path of totality, remove your solar filter only when the moon completely covers the sun’s bright face and it suddenly gets quite dark. Experience totality, then as soon as the bright sun begins to reappear, replace your solar viewer to glance at the remaining partial phases.
- An alternative method for safe viewing of the partially eclipsed sun is pinhole projection. For example, cross the outstretched, slightly open fingers of one hand over the outstretched, slightly open fingers of the other. With your back to the sun, look at your hands’ shadow on the ground. The little spaces between your fingers will project a grid of small images on the ground, showing the sun as a crescent during the partial phases of the eclipse.
(Photocredit: National Park Service)